Yes. A 3-1/2" chamber will accept 2-3/4" & 3" & 3-1/2 shells
A 12 gauge shotgun cannot fire 20 gauge shells.
You could eaither shoot dove with a 20 gauge shotgun or a 12 gauge shotgun. You should also use a bird shot shells
Yes, you can shoot 2 1/2,2 3/4, and 3 inch shot gun shell in that barrel.
You are free to use both 2 3/4" as well as 3" shells in the CD gun.
Technically, trap guns are shotguns that shoot shot shells that are filled with pellets. These are not "bullets" However, you can shoot "slugs" from a trap gun. Slugs are solid lead projectiles much like bullets. 12 ga. slugs are very powerful and can be used to hunt deer in many states.
You need to have it examined by a gunsmith
In general, yes, since the 2-3/4 is a lower power shell. If the gun is a semi auto, it may not cycle properly. You didn't identify the gun (there are a lot of model 88's). You will want to clean the chamber at the forcing cone very well after you shoot it to prevent powder buildup when shooting the shorter shells.
yes but you have to shoot with a fully licenced person
No, you can not shoot anything but 12 gauge shotgun shells through a 12 gauge shotgun. Never use any ammunition other than what the firearm was designed for.
The length of the chamber in a 2 3/4 inch chambered shotgun is 2 3/4". The longer 3" shotgun shells will not fit in the chamber, being 1/4" too long. You can shoot 2 3/4" shotgun shells, of the correct gauge, in a 3" chambered shotgun.
@ turn of the century, DO NOT USE MODERN AMMUNITION!!!!!!!!!!!!!!!!!!!!!!!!! DANGER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! UNSAFE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Only if it is chambered for them. Have it examined by a good gunsmith